The verb TO SPEAK and its synonyms

Very often Russian language learners can be met a common mistake in the proper use of synonyms of the verb "ГОВОРИТЬ".

There are several versions of this verb. Let's consider the main ones on examples.

СКАЗАТЬ

It is used when it is necessary to inform the interlocutor or group of people about any information. This can be a short news of a person, an instruction to do something, or the transmission of someone's words.